Coded information transmit-receive communications system



Oct. 22, 1963 B- R. LESTER CODED INFORMATION TRANSMIT-RECEIVECOMMUNICATIONS SYSTEM Original Filed Oct. 1. 1952 2 sheets sheot 1FlG.lu

INVENITORI 6 BURTON R. LESTER,

BY ms ATTORNEY.

Oct. 22, 1963 B. R. LESTER 3,108,255

CODED INFORMATION TRANSMIT-RECEIVE COMMUNICATIONS SYSTEM 0riginal FiledOct. 1, 1952 2 Sheets-Sheet 2 FlG.lb 27 INVENTOR: 59 BURTON R. LESTER ll i 51 53 HIS ATTORNEY.

United States Patent 3,1ll8,255 CQDED lNlFtllllMA'lilONTRrlNSlilllT-REEKVE @GMMUNIQA'HQNS SYSTEM Burton ester, Ealdwinsville,Nil, Sage Drive, Warren Township, Elainiield, NJ.)

firiginal application Get. 1, i952, Ser. No. 312,516, new

Patent No. Laid-5,616, dated July 29, 1958,

and this application Nov. 29, 1957, Ser. No. 7tl3, i7@

'7 Claims. (6i. 340-150) My invention relates to communications systems,and more particularly, to such systems in which stereotyped messages tobe communicated between selected stations are preliminarily encoded andtransmitted as a pulse- Inodulated carrier, to a distant receiver atwhich the coded message is detected and decoded to provide a visualindication of the message. This application is a division of US.application, Serial No. 312,516, which has issued as US. Patent2,845,616.

An object of the invention is to provide a novel communications systemin which a considerable reduction in transmitter time can be effected bycoding individual messages of a selected group of stereotyped messagesand then transmitting only the code designation of the message.

Another object of the invention is to provide a cornmunications systemof the type referred to, wherein the received messages are displayed forvisual observations, whereby the time required for receiving is onlylong enough to place into operation a decoding mechanism.

A further object or": the invention is to provide a communicationssystem of the herein-mentioned type in which the receiving apparatus andthe transmitting apparatus are substantially identical, and furtherwherein the apparatus for coding the message can be used, withoutmodirication, for decoding the received message.

Still another object is to provide a system of the type mentioned havingpulse-transmitting means and pulsereceiving means and means operable onthe actuation of said transmitting means to render inoperative saidreceiving means throughout the period of pulse transmission.

Yet another object is to provide a novel and improved coding anddecoding mechanism having a first part operable to translate data in adecimal form into a binary digital representation and a second partoperable to translate data in binary digital form into a decimal form,said mechanism including means for rendering said first part inoperativethroughout the period of operation of said second part.

The novel features which i believe to be characteristic of my inventionare set forth with particularity in the appended claims. My inventionitself, however, both as to its organization and method of operation,together with further objects and advantages thereof, may best beunderstood by reference to the following description taken in connectionwith the accompanying drawings in which:

FIGS. 1a and 112, read in side by side relation, illustrate a completetransmit-receive station according to the invention, and

FIG. 2 is a diagram representing a sequence in the binary system ofnumeration employed in the coderdec-oder apparatus of the invention.

A communication system according to this invention may comprise aplurality of transmit-receive stations, each station being identicallyconstituted and adapted to transmit and receive, at any given instant, aselected one of a plurality of predetermined or stereotyped messages.The system can be generally employed whenever and wherever it isrequired to transmit a large number of such messages to a number ofindividual receivers, and in one practical embodiment, one such stationwas located i .011 the ground, and other stations were mounted in air-3,198,255 Patented Get. 22, 1963 craft providing a communication,navigation, trai'lic control and ground-to-air transmitting link. Such alink, it will be noted, is capable of sending both information andcontrol signals to one or more aircraft within the line of sight of oneradio-frequency channel.

For the purpose of simplifying the present description, the number andtypes of stereotyped messages that can be tr nsmitted and. received hasbeen arbitrarily reduced to indicate generally the scope of theapparatus without unnecessarily burdening the description withrepetitive details. Thus, in the description that follows, it will beconsidered that information concerning bearing and elevation only aredesired to be transmitted and that for each type of information thereare 256 dillerent predetermined messages that can be sent. it will, ofcourse, be understood that these types and numbers of messages areexemplary only and that other types and numbers can be employed, as forexample, distance, temperature, and related data as well as a variety ofcommands and order such as Report, Repeat, Identify, etc.

in FIGS. 1a and 1b, a transmit-receive station is shown compnising anoscillator ll, shown in the lower left-hand corner of FIG. la, which maybe or" any suitable conventional type for producing radio-frequencyoscillations at a desired frequency value. The oscillator 11 is adaptedto be keyed by a modulator 13, which may also be of any suitableconventional variety to cause the emission by oscillator ll of positiveand/or negative pulses at a suitable rate, say from 20 to 30 pulses persecond, over a 'bandwith of from 200 to 300 cycles per second. A trainof pulses including, in the illustrated embodiment, 10 equi-amplitudeequi-duration and equi-spaced pulses of positive and/or negativepolarity, carries the message or intelligence to be transmitted coded inbinary form, and such a train is applied to an antenna (not shown) bymeans of transmission line 15. Similar trains of pulses, radiated fromanother station, after reception by the antenna, are fed to receiver anddetection apparatus 17 for subsequent decoding and visual presentation.

The elements or" my coder-decoder apparatus by means of which themessage or intelligence to be transmitted is coded in binary formpreliminarily to actuation of the modulator l3, and which also functionsto decode the received pulse train to yield the intellige ce conveyedthereby, will now be described in detail.

The coder-decoder apparatus comprises four coding wheel assemblies CW CWCW CW which are identically constructed and operate in identical fashionto translate data, information or intelligence of any type or form intoa binary digital form and conversely to translate such data informationor intelligence in binary digital form into its original form. Theassemblies CW; and CW in the illustrative embodiment, are foraccommodating intelligence of the first type, say elevation, andassemblies CW and CW are for accommodating intelligence of the secondtype, say bearing. Additional assemblies can, of course, be providedwhere it is desired to ccommodate additional types of intelligence.

As noted, the coder-wheel assemblies are identical in construction andin mode of operation. Accordingly, the construction of one suchassembly, say assembly CW will be described in detail, it beingunderstood that the corresponding elements of the other assemblies aresimilarly constructed for similar operation.

Coder-wheel assembly CW comprises an array of rotatable cams C C C and Cmounted for conjoint rotation on a common shaft 19 which also carries aratchet 21 of a stepping switch 23. The stepping switch 533 can be ofany suitable type Well known in the art and having a movable core 12that carries a pawl 14 in engagement with the ratchet 21 so that, whenthe winding is energized, the core 12 is drawn downward against the aaction of a spring carrying the pawl into engagement with the next toothof the ratchet 21. The downward movement of the core also opensinterrupter contacts, subsequently to be described, thereby breaking theenergizing circuit of the winding. The core is thereupon returned to itsunattracted position by means of the spring .16, causing the pawl 1'4 tonotch or step the ratchet 21 one step. Cam C is formed with eightequi-angularly spaced high portions as at 25 and an equal number ofequiangular ly spaced low portions as at 27 interspersed between thehigh portions 25. Cam C adjacent cam C is formed with one half thenumber or four high and low portions, and earns C and C are respectivelysimilarly formed with half the number of high and low portions of thecams next adjacent thereto. Associated with each cam are respectivespring-biased cam followers 2?, 31, 33 and 35 each of which carries apair of contactors, as at 37 and 39 for actuating respective pairs ofcontacts 41, '43 and 45, 47. it will be noted that one contact of eachpair of contacts is normally open and the other is normally closed.

The coder-wheel assemblies 'CW I, CW and CW are similarly constituted ofidentically arranged sets of cams, identified as cams C C C and C inassembly CW C C C and C in assembly CW and C C C and C in assembly CWThe stepping-switch and ratchets in the assemblies CW CW and CW are alsosimilar to corresponding elements of assembly CW and these areidentified in the drawing by the numerals 24, 26, and 28 referring tothe stepping-switches and numerals 30, 32, and 34 referring to theratchets.

The position of a given cam will, for this description, be regarded asnormal when the associated follower is on a high portion of the cam andthe open or closed condition of the related contacts will be determinedaccordingly. Thus, in the illustration, cam C is in the actuatedcondition, since the fol-lower 29 is at a low portion 27 of the cam.Hence, the contacts 41 and 45, which are normally open, are presently inclosed condition. The cam C is instantly in the normal position.

The arrangement of the high and low portions and 27 on the cams C C isdiagrammatically shown in developed form in FIG. 2, in which shadedareas, as at 49, correspond to the high portions 25 and unshacled areas,as at 51, correspond to the low portions 27. The developedrepresentation of FIG. 2 thus consists of four vertical columns 53, 55,57 and 59 of alternatively spaced shaded and unshaded areas, the column53 containing eight shaded areas and eight unshaded areas, the column 55containing four shaded and four unshaded areas, column 57 having halfthe number found in column 55, and column 59 having half the numberfound in column 57.

If, in the diagram of FIG. 2, the shaded areas represent zeros and theunshaded areas represent ones, there is thus presented a representationof a binary sequence in which the horizontal rows considered from top tobottom correspond to 0000, 0001, 0010, 0011, etc. correspondingrespectively to the decimal numbers 0, 1, 2, 3, etc., shown at the righthand edge of the diagram. The numbers '1, 2, 4, and 8 across the top ofthe diagram, indicated by the presence of an unshaded area at theintersection of a given row and the respective column, the presence ofthe corresponding decimal number. Thus, in the row corresponding todecimal 13 or binary 1101, non-shaded areas are found in the 8 column,the 4 column and the 1 column, indicating the presence of an 8, a 4, anda 1 in the decimal number, which together make up the decimal 13.

Returning now to FIGS. 1a and 1b, it will be seen that the instantsetting of the cams C -C of coding-wheel assembly CW with the followerof cam C on a high portion and the followers 31, 33 and 35 of the wheelsC C and C on low portions, when interpreted in View of the binarysequence diagram of FiG. 2, corresponds to i a binary 0111 or decimal 7,and the decimal number 7 is, accordingly, found on an indicia wheel 61that is mounted on the cam shaft 19 for rotation with the cams e c.,.Also, it will be observed that when C -C are rotated one notch, as bythe actuation of the steppingswitch 23, the follower 35 of cam C willhave dropped to the low portion of the cam C; while the followers 33, Siand 29 of the cams C C and C will have been raised to high portions ofthe respective ca-ms, so that the setting of the coding wheel assemblyCW; now corresponds to the binary 1000 or decimal 8.

The description just completed of the construction of coder-wheelassembly CW whereby the instant setting of the earns C 43 corresponds toa predetermined binary number, which in turn is translatable into acorresponding decimal number applies identically to the coder-wheelassemblies CW CW and CW the latter assemblies being of essentially thesame form as assembly CW There follows now a description of the circuitconnections of the individual contacts of the cam switches of respectivepairs of coder-wheel assemblies, and for simplification of thedescription, only representative connections will be described, it beingclear that the corresponding connections for the remaining cam switchesare similarly made.

Thus, turning again to coder-wheel assembly CW and particularly theupper pair of cam actuated contacts 41 and '43, it will be observed thatsaid contacts 41 and 43, here shown actuated, are respectively seriallyconnected to normally closed and normally open relay-operated contacts63 and 65. The series-connected contacts '41 and 63 are connected inshunt with the series-connected contacts 43 and 65, one side of theshunt arrangement being grounded and the other side being connected, asby conductor 67, to the winding 69 of the stepping switch 23.

The contacts 63 and 65 are actuatable by means of an electromagneticrelay R which as shown, is the extreme right-hand one of a bank of eightsimilar electromagnetic relays R R which function as data storagedevices employed in the message-reception phase of the transmit-receivestation of this invention. Each relay of the bank il -R is provided witha winding, as at 70 for relay R which upon energization, operates toactuate a pair of relay contacts associated with the uppermost pair ofcam contacts of each of a pair of cam elements in the coder-wheelassemblies. Thus, relay R controls the actuation of the'relay contactsas and 65 that are respectively connected to the cam contacts 41, 43 ofcam C in assembly CW Relay R also controls the actuation of a secondpair of relay contacts 71, '73 that are connected to cam contacts 75, 77of the cam C in coderwheel assembly CW For a reason that will becomemore apparent as the description of the structure and operation of theapparatus proceeds, the uppermost pair of cam contacts of each cam (l -Csuch as the contacts 41, 43 of cam C and contacts 75, 7'7 of cam C aretermed sensing contacts inasmuch as these contacts operate to sense thepotential at one terminal of the winding of the associated relay R Asshown in the case of relay R for example, one terminal of the winding 70thereof is connected, as by conductors 79 and 81, through a normallyopen relay contact $2, to a source of positive potential, conventionallyindicated by 3+, the other terminal of winding 70 being connected, as byconductor 83, to a tap marked 1 on a mul-t-iposition switching element Shaving a movable wiper 84. A holding contact for relay R is connectedbetween the conductor S3 and ground so that, upon impulse energizationof relay R by a pulse of positive polarity in a manner subsequently tobe described, the contact 85 is made, and if contact 82 is in closedcondition, the relay R is sealed in through a circuit extending from 3+,through contact 82, conductors 81 and 79, winding 70 and contact 35 toground.

It will be helpful to note for the present that a relay R shown in thelower left-hand portion of FIG. 1a is provided with a winding @ll oneterminal of which is connected to 16+ and the other is adapted to beconnected to ground through the armature 92 of a polarized relay PR. Asshown, the winding of the polarized relay PR is adapted for cnergizationby the pulsed output of the receiving apparatus l7, which as notedabove, comprises a pulse train of positive and negative pulses accordingto the information or intelligence contained in the received message.The relay PR is polarized so that a positive received pulse causesdeflection of the armature 92 to the left resulting in the energizationof relay R and the consequent actuation of contact 88 as well as asecond contact $4. A negative received pulse causes deflection of thearmature 92 to the right resulting in the energization of a relay R theenergization of which closes a contact 96, the function of which issubsequently to be described.

Returning now to the bank of relays il -R it will be seen that oneterminal of the winding of each relay is connected to a respective tapof the switch S the taps being appropriately marked 2 for relay R 3 forrelay R etc., so that as the wiper 34 is stopped around, cont-act ismade successively with the winding of each relay R R the other terminalof each winding being connected in common, by conductors 79 and 81,through contact 82, to 13+.

Switch S is provided with three additional taps marked 9, N and ti,respectively, the 9 and N taps being open and corresponding to the powerstage and home or normal position, respectively, of the switch, $215will appear. The ti tap is connected to one terminal of the winding of amessage-selector relay R the other terminal of said winding beingconnected to the common connection formed by conductors '79 and ill.Relay R is also provided with a holding contact 98 similar to theholding contacts of the storage relays Il -R as exemplified by contact33 of relay R and in addition, relay R iactuates a pair of contacts 1%and 1&2, one of which is normally closed and the other normally open.One side of each of the contacts lllltl and 1&2 are connected jointly,by conductor 1% to the wiper res of a power control switch S for thecoder-wheel assemblies UN -CW the wiper res and wiper 84 being mountedon a common taxis, indicated at 1%, for conjoint rotation. The switch Sis provided with a single segmental contact Mil disposed in a positioncorresponding to the number 9 position of the switch 8 so that when thewipers 84 and res step off the 8 position and on to the 9 position, acircuit is made from E+ through normally closed contacts iii and of apair of relays R and R respectively, to be described hereinbeiow.

The other sides of the contacts 1% and M2 of the message selector relayR are connected to the windings of selected pairs of the steppingswitches in the code.-

wheel assemblies CW -CW Thus, contact 1% is connected in common towindings of stepping switches 23 and 24 of assemblies CW CWrespectively, the connection being affected through conductors 116 andlid and normally-closed interrupter contacts M2 and 12d? of the switches23 and 24, respectively.

Similarly, the contact M92 is connected in common to the windings ofstepping switches 26 and 28 of assemblies CW and CW respectively, theseconnections being effected through conductors 12 i and 126 andnormallyclcsed interrupter contacts 12% and 13% of the switches 26 and28, respectively. p

The stepping action of wipers d4 and 1% of switches S and 3respectively, is accomplished by means of a master stepping switcharrangement MS, comprising a conventional stepping switch having awinding 109 and a ratchet 111, the latter being suitably mounted on theaxis 1G8 to produce rotative movement thereof. in a manner well known tothose skilled in the art, energize.- tion of the winding 3109 from asuitable source, here indicated conventionally by 3+, causes anarmature-pawl Iii-.3 to be drawn down a notch of the ratchet compressinga spring so that, upon deenergization or" the winding 109, the pawl ispushed upward stepping the ratchet around one step or notch. The circuitfrom 13+ through the winding M9 is completed to ground by means ofconductors 1'25, 117, and 137, and either of the contacts 94 and as ofrelays R and R respectively, depending on which of the two is actuated.It will be recalled that contact is closed in response to a positivepulse and contact is closed by a negative pulse. Thus, pulses of eitherpolarity are eifective to close one or the other of the contacts 94 orQ6 causing the energization of winding MW of the master stepping switchMS, which, in turn, produces stepping movement of the ratchet 111. Thestep-by-step rotation of the ratchet 111 results in a correspondingmovement of the axis Fltld and the wipers 84 and as well as wipers lid,121i, 123 and 125 of associated rotary switches S S S and Srespectively. As shown, all the wipers are ganged on the axis 1% forconioint movement in response to stepping or notching or" the switch MS.

Since the switches S and 8., are utilized in the message-transmissionphase of the operation of the system, the description of the circuitryassociated therewith will be given later hereinbelow.

Switches 8;, and S are off-normal contacts, so-called, inasmuch as theyprovide open contacts when the master stepping switch MS, as evidencedby the position of the wipers 55 5, res and 1119, is in the normalposition N, and provide closed contacts for all other positions of themaster switch. To that end, the switches S and S may each be formed witha substantially circular conductive strip H7 and 129 having insulatedgaps 132 and 13 1, respectively, at positions thereon corresponding tothe normal position N.

As shown, off-normal contact 8;, is connected, as by conductor ii! and aconductor 135 across a normallyopen relay-operated contact 1136 and theshunt pair is connected at one side to 8-}- through the winding Hi9 ofthe master stepping switch MS. The same side of the shunt-connectedcontacts S and 136 is connected to ground, as by conductor 137, throughthe contacts 94 or 96 of relays R or R respectively.

The other side of the shunt-co=nnected contacts 8;, and 135 is connectedto ground through either of a pair of branched paths, one said pathincluding a series connec tion of a normally-open relay contact 133 anda normally-closed relay contact 139. The other path to ground isprovided by a series connection of a normally-closed interrupter contact14d of the master stepping switch MS, a normally-open relay contact M lland a normallyclosed relay contact 14 2. Relay contract ml is operatedby a time-delayed operating relay R having a conventional means, such asa dashpot Me for delaying the operation of the relay by a predeterminedshort time interval. Contact 142 is operated by relay R Gil-normalcontact S is connected, at one side, to 3+ by conductor 14-? through thewinding 144 of a relay R and on the other side to ground by conductor3145. The grounded side of the oil-normal contact S is also connected,through the normally-open contact 33 of relay R and conductor he, to thewiper 34 of switch S To complete the description of so much of thesystem as is utilized in the reception of a message, it will be notedthat the master stepping switch MS is provided with a second interruptercontact 143 which on one side is connected to 13-}- through the windingof the relay R and to ground through a normally-open contact 1% of relayR in series with normally-open contact 152 of relay R The other side ofinterrupter contact 14-8 is connected to ground through conductor 154and a series connection of normally-closed second interrupter contacts15-23, 153, res and 162. of the stepping switches at, 2%, 2dand 23;,taken in that order.

The operation of the receiving portion of the system described to thispoint can now be explained with reference to a received message. Asnoted above, a message consists of 10 pulses each of which can bepositive or negative according to the intelligence contained therein.Also, the polarized relay PR is po led to effect energizetion of relay Rin response to the reception of a positive pulse and to efiectenergization of relay R in response to reception of a negative pulse.

In the quiescent period, before the reception of any pulse, only thewinding of relay R is energized, the euergization thereof being effectedby the circuit extending from 13+, the winding of relay R interruptercontact 148 of the master stepping swi-tch MS, conductor 154, and theinterrupter contacts 156, 158, 161i and 162 of the coder-wheel assemblystepping switches. All the other relays and all the stepping switchesare deenergized, and all the wipers of the switches 5 -5 are on thenormal position N.

Now, if a pulse of either polarity is received, so that either contact94 or contact 96 is closed, winding it)? of the master stepping switchMS is energized through conductors 115, 117 and 137, and at thetermination of the pulse, the ratchet 111 is stepped one notch movingall the wipers oi the normal position N, wiper 84 of switch S contactingthe tap, and wipers 123 and 125 contacting the segments 127 and 129,respectively, thus closing the off-normal contacts S and S The closingof contact S results in the energization of relay R and the opening ofthe interrupter contact 143 results in the deenergization of R In theinterval between the termination of the first pulse and the reception ofa second pulse, winding 169 of switch MS is deenergized and theinterrupter contact 148 is again closed by the upward thrust of theannaturepawl 113, again energizing the winding of relay R But, as noted,relay R is delayed a short time interval in its operation by the dashpot1%, so that its contacts are not instantly closed. Thus, if a secondpulse is received before the contacts of relay R are closed, the switchMS is stepped a second notch thereby in exactly the same manner as justdescribed.

However, it may happen that the first pulse received is merely a randomnoise pulse and not followed by a second pulse and successive pulses inregular order and timing. In that case, assuming no pulse is receivedafter the first by the time that relay R has operated to close thecontact 150, the reenergization of relay R results in the sealing in ofthe relay R through the closed contact 150 and the actuated contact 152.of relay R Then, since contact 141 of relay R and off-normal contact Sare both closed, the master stepping switch MS is interruptedly operatedthrough its interrupter contact Mil and the normally-closed contact 14-2of relay R until the switch MS steps around to the normal position Nwhereupon the oii-normal contacts 8 and S open deenergizing the winding109 of switch MS and the winding 14% of relay R The operation of therelay R results in the breaking of contact 114 removing B+ from thewindings of the stepping switches 23, 24, 2s and 25, thus assuring thatthe coder wheel assemblies do not operate as the master stepping switchMS steps around to its home position N after the reception of a randomnoise pulse. The mode of operation in response to a random noise pulsehas proved to be very useful in eliminating spurious and erroneousindications and accordingly constitutes an important aspect of thesystem.

Where the first pulse, which it will be observed, is preparatory onlyand serves (1) to step the master switch MS oh? the normal position, (2)to deenergize relay R and (3) to energize relay R is followed by asecond pulse before the time delay period of relay R has expired, relayR is not sealed, in but instead the interrupter contact 149 is brokenbefore relay R becomes reenergized. All the received pulses in thesequence, since they are spaced less than the time delay period, operatethus to step the switch MS one notch. However only positive pulses thatactuate relay R cause the closing of contact 38 of relay R which isconnected to the Wiper 84 of switch S So, as the wiper 84 steps aroundcontacting the taps 3-3 that are connected respectively to the windingsof the relays R R certain ones of these relays are sealed in by thepositive pulses while those other relays receiving negative pulsesremain unsealed and unenergized. I

The second pulse in the received message determines the type of messagethat is being received. For example, if the second pulse is positive,the message selector relay R is energized and sealed in through itsholding contact 98. Also, contact tilt) is closed, so that upon thesubsequent closing of contact S the stepping switches 23 and 2.4- ofcoder assemblies CW and CW are energized, cor responding to informationconcerning hearing. If the second pulse is negative, relay R isunaffected and not sealed in. Thus, contact m2 is closed, and, on theclosing of switch S the stepping switches 26 and 28 of coder-wheelassemblies CW and CW are energized yielding elevation information.

The remaining eight pulses of the received train of pulses contain thestereotyped message, and cause the master stepping switch MS to steparound through the remaining 8 positions, e.g. to the open position 9 ofthe S switch, various ones of the relays R -R being energized and sealedin, and others being unenergized and not sealed in according to thepolarity of the successive pulses. When the switch MS reaches the 9position, the power control switch S is closed by the contacting ofwiper 106 and segment 110, connecting the selected pair of coder wheelassemblies CW; and CW or CW and CW to B-[- through the closed contacts112 and 114, conductor 3.64, either one of the contacts 10%) or 162, andthe conductors 116 and 118 or the conductors 124 or 126.

The stepping switches of the selected coder wheel assemblies then steparound, by means of the interrupter contacts in series with therespective windings, driving the associated cams, until the position ofthe cam switches is attained for which the connection to ground isbroken by the cam contacts.

When each of the stepping switches of the selected coder-wheelassemblies comes to rest with the (respective interrupter contactsclosed for a period greater than the time-delay period of the relay Rthe latter is then operated and sealed in through the contact 152 ofrelay R whereupon the master stepping switch MS steps one more notch tohome or normal position N, being energized through the ofi-normalcontact S the interrupter contact 140, and the contacts 141 and 142 ofrelays R and R respectively. At the home position N, the opening ofoft-normal contact S deenergizes the relay R and stops the masterstepping switch MS. Also, the open ing of contact 82 of relay R removesB,+ from the relays Ro-Rg and unseals them. The instant position of thetwo selected coder-wheel assemblies then corresponds to the intelligencecontained in the received message.

In the transmission of a message by the apparatus of my invention, apair of coder-Wheel assemblies is preliminarily selected according tothe type of message sought to be sent. The cams of the selected pair arethen manually rotated, as by manipulation of the indicia wheel 61, forexample, until the desired position of the cams is attainedcorresponding to the message. This rotation sets the various contactsassociated with the cams corresponding to the contacts 45 and d7 of camC in coder-wheel assembly CW Thus, for transmission, the lower-most pairof contacts associated with each cam (D -C are employed. And, as notedhereinabove, these contacts are interconnected through the switches Sand S of the master stepping switch MS. 7

A more complete description of the switching and relay elements employedin the transmission operation will now be given. Again, since theconnections of the individual contacts of the respective cams Q-C aresimilar and symmetrical, for simplicity, the description of the conareasnections of the contacts 45 and 47 cam C will be taken as illustrativeof all the other connections.

One of the pair of contacts presently concerned is normally open theother being normally closed. As shown, cam C is in the actuate-dcondition since, as noted above, the follower is at a low 27 on the cam.Thus, the normally-open contact 45 is shown closed and the normallyclosed contact 47 is shown open.

One side of each of the contacts 45, 47 is connected, in common, byconductor 164 to tap ll of the switch S the other side of contact 45being connected, by conductor 166 to the negative bus 168 of a source ofmodulating voltage, while the other side of contact 47 is connected tothe positive bus 170 of the source.

The lower-most pairs of contacts associated with cams C 43 are similarlyinterconnected to the buses 1.68, 17d and to the taps 2 through 8respectively of the switch S "ap 9 of switch S is open and taps N and iiare connected respectively to negative bus 168 and positive bus 17%. Theconnection of the tap to the positive bus insures the provision of apositive pulse in the sec ond pulse position of the train indicating themessage type corresponding to coderwheel assemblies CW; and CVVII.

The lower-most pair of normally open and normally closed contacts ofcams C -C are connected to the buses 168 and 170 and to the taps 1through 8, respectively of the switch S in a manner similar to thatdescribed iabove. Tap 9 of switch S is open and taps N and 0 thereof areeach connected to the negative bus 168. The connection of the 0 tap ofswitch S to the negative bus ensures the provision of a negative pulsein the second pulse position of the train indicating the message typecorresponding to coder-wheel assemblies CVIH and CWIV.

The wiper 119 or" switch S is connected to the modulator 13 by conductor172, through normally-open contacts 174 and 176 of a pair of relays Rand R respectively, and a normally-closed contact 178 of a time-delayoperate relay R of which the time-delay operation is conventionallyillustrated by the dashpot device 13%.

The wiper 121 of switch S is connected to the modulator 13 throughconductor 182, a normally-open contact 184 of relay R conductor 186, andthe contacts 174 and 178.

A pair of pushbutton switches P and P actuating contacts 188, 196 and192, 1%, respectively, are shown in the lower left-hand portion of FIG.la, either of which, when momentarily closed, initiates the transmissionprocess. One side of each of the contacts ll8%19 4 is connected toground through a normally-closed contact 1% of relay R Contact 190 ofbutton P and contact 194 of button P are jointly connected through thewinding of relay R to B+. Contact 188 of button P is con nected to 13+through the winding of relay i1 and contact 192 of button P is connectedto 13+ through the winding of relay R Contact 192 is also connected toground through a normally-open contact 197 of relay R in series with anor1nally-open contact 2198 of relay R The winding of relay R isconnected between 13+ and ground through a pair of branched paths one ofwhich includes a normally-open contact 2% of relay R the other pathbeing provided by a series connection of normally-open contacts 202 and204 of relays R and R respectively.

The winding of the time-delay release relay R is connected between B+and ground by a series circuit of a normally-open contact 296 of relay Rand a normallyclosed contact 208 of relay R The winding of thetime-delay operate relay R is connected between B+ and ground through anormally-open contact 210 of relay R Relay 19 actuates an additionalnormally-closed contact 212, which, as shown, is in the line feeding theinput circuit to the receiver and detection apparatus 17 to disconnectthe same during the transmission process.

In the transmission of a message, and assuming that the indicia wheelshave been rotated to the indicated portions (each displaying a decimal7), the closing of pushbutton P causes information in the coder-wheelassemblies CW and CW;; to be transmitted. The button P should be heldclosed long enough for the master stepping switch MS to step away fromthe home or normal position N. The sequence of operation will now bedescribed.

Relays R and R are momentarily energized through the normally-closedcontact 1% of relay R and contact 136 of relay R in closing, shunts theoff-normal contact S Also, when contact 260 of relay R closes, relay Ris energized, which by the closing of its contact results in theenergization of relay R The closing of contact 1.7 of relay R andcontact 176 of relay R results in the application of a negative voltagefrom the N position of switch S to the modulator 13 through theconductor 172 and contacts 176, 174 and 17b to form the first outputpulse.

The closing of contact 138 of relay R also results in the energizationof the winding 109 of the master stepping switch MS through contact i 36of relay R contact 138 of relay R and contact 139 of relay 21, so thatthe switch MS steps one notch to the 0 position of switch S As soon asthe switch MS steps from the home position N, relay R is deenergized bythe breaking of interrupter contact 3143; the olf-normal contact Scloses causing energizaticn of relay R through the circuit includingconductors 143 and 14-5. Relay .17 actuates contacts 202 and 1% thereof,sealing in relays R and R respectively.

All the foregoing operations take place in a relatively brief timeinterval and, as mentioned above, pushbutton P may be released as soonas the master stepping switch steps off the home or normal position N.Release of the button P causes relay R to drop out since the latter isnot sealed in. The first output or preparatory pulse is terminated bythe operation of the time-delay operate relay R which is energized andoperated a brief interval after the closing of contact 215? of relay RThe operation of relay R also opens normally-closed contact 139 thereofthereby deenergizing the winding 109 of the master stepping switch MSplacing the latter in readiness to be stepped again.

After a brief release delay from the time that relay R operates, relay Ris deenergized by the opening of normally-closed contact 2% of relay Rrelay R is deenergized due to the opening of the normally-open contact214 of relay R and relay R is reenergized because of the closing ofnormally-closed contact 2438 of relay R Thus, the modulator 13 is againsupplied with a voltage, this time a positive pulse from tap ii ofswitch S through conductor 172, contacts 176, 174 and 178, indicatingthe message to follow is of the type characterized by codenwheelassemblies CW; and CW This pulse is terminated upon the operation of thetime-delay operation relay R opening its normallyclosed contact 178. Thesecond pulse, being positive operates to seal in the relay R on thereceiving station routing the message to the 8;, switch thereof and tothe coder-wheel assemblies CW; and CW The cycle of pulse transmissionand stepping continues as described, each pulse transmitted being ofpolarity depending upon the setting of the corresponding pair oflowermost contacts, such as the contacts 45 and 47 of cam C which asdescribed above, is controlled by the setting of the coder-wheelassemblies.

It will be noted that if pushbutton P had been actuated, the secondpulse would have been negative in polarity, the (3 tap of switch S beingconnected to the negative bus 168. Such a negative second pulse has noeffect on relay R in the receiving station resulting in the routing ofthe message to the switch 8.; thereof and amazes thence to thecoder-wheel assemblies CW and CW Otherwise, the operation oftransmission from the assemblies CW and CW through the contact 184 ofrelay R instead of the contact 176 of relay R is the same as describedin connection with the assemblies CW and CW The stepping of switch MScontinues until switch MS reaches home position, whereupon theoff-normal contact S opens deenergizing winding 144 of relay R breakingcontact 152. thereof. Relay R is again energized through the interruptercontact 143 of the switch MS and the interrupter contacts 156, 15%,116i) and 162 of the coder-wheel stepping switches 26, 23, 24 and 23,respectively, and the apparatus is again ready to receive or trans mit amessage.

It is to be noted particularly that when relay R is energized by pushingone or the other of the buttons P or P the normally-closed contact 142thereof opens so that the winding N9 of the master stepping switch MS isnot at first energized through the interrupter contact 14o thereof, butrather through the contacts 139 and 138 of relays R and R respectivelyand contact 136 of relay R Thus, when the switch MS steps off the homeposition N, and energizes relay R through the off-normal contact S relayR is then sealed in through contact .232 of relay R and contact 2% ofrelay R Relay R is thus held in during the entire transmittingoperation, and by the opening of normally-closed contact 212 thereof,the amplifier 17 is isolated from the transmission line 15 so thattransmitted signals are not fed back to the transmitting apparatus.

Also, during the entire transmission period, the normally-closed contact112 of relay R being then in open condition, isolates from 13+ theoperating windings of the stepping switches 23, 24, 216 and 28 of thecoderwheel assemblies so that they are maintained deenergized. Absentsuch as isolation contact, the coder-wheel stepping switches would tendto position themselves to correspond to the deenergized relays li -Rwhen the master switch MS reached the position.

It Will be observed further that the ground connection from pushbuttonsP and P is made through normally-closed contact 196 of relay RAccordingly, transmission of a message cannot be commenced except whenthe switch MS is in the normal position N rwhen relay R is deenergized.In this manner, transmission of a message is prevented during the timethat the switch MS is stepping around to normal or home N as a result ofa random noise pulse or during the reception of a message.

The width and spacing of the transmitted pulses, it will be noted, aredetermined accurately and solely by the time delay periods of the relaysR and R of which the normally-closed and normally-open contacts 178 and174, respectively, are in series circuit with the input of the modulator13. The pulse width and spacing is thus equal to the respective periodsof time during which the relays R and R are simultaneously energized anddeenergized.

While I have illustrated and described particular embodiments of myinvention, it will, of course, be understood that various changes andmodifications may be made, and I contemplate by the appended claims tocover all such changes and modifications as fall within the true spiritand scope of my invention.

What I claim as new and desire to secure by Letters Patent of the Unitedctates is:

1. A transmit-receive station for a communication system comprising awave energy transmitter and a wave energy receiver mutually adapted forexchanging information with a similar remote station linked therewith;translating means for encoding and decoding having dual actuation meansand condition responsive elements coupled with both said actuation meansand storing said information corresponding to actuation in coded form,one

of said actuating means being locally actuated by decoded information,means coupled to said condition responsive elements for transformingsaid coded information into a train of electric impulses having acharacteristic corresponding thereto, means coupling said train ofelectric impulses to said transmitter for emission to a remote stationof a pulse modulated wave corresponding to said train of impulses, meanscoupled to the output of said wave energy receiver for transforming areceived train of electric impulses into code-d information, additionalmeans for storing information coupled to said last recitedtransformation means, means for energizing the other of said actuatingmeans to thereby sweep said translating means through successiveconditions, means coupled jointly to said condition responsive elementsand to said storage means for sensing correspondence between the settingof said translating means and said stored information and therebytie-energizing said second actuating means at correspondence.

2. A transmit-receive station as set forth in claim 1, wherein saidfirst and second transformation means are separate switching elementshaving common driving means.

3. As set forth in claim 1, wherein said coded information is binaryinformation and said condition responsive elements and said additionalstorage means each comprise a plurality of bistable elements.

4. A transmit-receive station for a communication system comprising awave energy transmitter and a wave energy receiver mutually adapted forexchanging information with a similar remote station linked therewith;translating means for encoding and decoding having dual actuation meansand dual condition responsive elements coupled with both said actuationmeans and storing said information corresponding to actuation in codedform, one of said actuating means being locally actuated by decodedinformation, means coupled to one group of said condition responsiveelements for transforming said coded information into a train ofelectric impulses having a characteristic corresponding thereto, meanscoupling said train of electric impulses to said transmitter foremission to a remote station of a pulse modulated wave corresponding tosaid train of impulses, means coupled to the output of said wave energyreceiver for transforming a received train of electric impulses intocode-d information, additional means for storing information coupled tosaid last recited transformation means, means for energizing the otherof said actuating means to thereby sweep said translating means throughsuccessive conditions, means coupled jointly to the other group of saidcondition responsive elements and to said additional storage means forsensing correspondence between the setting of said translating means andsaid stored information, and thereby dc-energizing said second actuatingmeans at correspondence.

5. A transmit-receive station as set forth in claim 4, wherein saidfirst and second transformation means are separate switching elementshaving common driving means.

6. As set forth in claim 4, wherein said coded information is binaryinformation and said condition responsive elements and said additionalstorage means each comprise a plurality of bistable elements.

7. As set forth in claim 6, wherein said first group and second group ofcondition responsive elements are two electrically separate groups ofswitching members, paired sets of which have common actuation means.

References Cited in the file of this patent UNiTED STATES PATENTS2,207,743 Larson July 16, 1940 2,397,604 Hartley Apr. 2, 1946 2,444,950Nichols July 13, 1948 2,689,950 Bayliss Sept. 21, 1954 2,719,284 RobertsSept. 27, 1955

1. A TRANSMIT-RECEIVE STATION FOR A COMMUNICATION SYSTEM COMPRISING AWAVE ENERGY TRANSMITTER AND A WAVE